A method for repairing underground cylindrical tubes, such as an open hole, an oil well, a gas well, a hot spring well, a water well, a reinjection well, or the like, is known. According to Patent Literature 1, a polyethylene film is wrapped around a radially expandable packer, and a covering member impregnated with resin is wrapped around the polyethylene film. The packer is then suspended down into the cylindrical tube and is radially expanded. The covering member is pressed against the inner wall of the cylindrical tube and is kept in that state until the resin is cured. Then, the packer is pulled up in order to complete the repair of the cylindrical tube.
According to Patent Literature 2, a covering member having a slit that longitudinally extends from one end to the other end is wrapped around a packer. The covering member is radially contracted in advance to an outer diameter that is smaller than the inner diameter of a cylindrical tube. Specifically, the covering member is wrapped around a radially expandable packer and is radially contracted so that circumferentially opposed ends of the slit overlap each other. An adhesive is applied to the outer surface of the covering member. The packer is then suspended down into the cylindrical tube and is radially expanded. The covering member is pressed against the inner wall of the cylindrical tube due to the elastic reactive force of the covering member. According to this method, the packer can be pulled up at an early stage because the covering member is held in the cylinder by its own elastic reactive force.    Patent Literature 1: JP2001-20653A    Patent Literature 2: JP2010-77767A